A compression test device for composite laminates with a large aspect ratio of length, width and thickness

Abstract

The present invention relates to a compression test device for a composite laminate with a large length-thickness ratio, belonging to the technical field of composite material testing. It can achieve that the two-side boundaries are kept in a simply supported constraint throughout the compression test process, and the simply supported condition is not easily changed at the moment of failure. The flatness of the loading plane on the length and width surfaces of the plate specimen is also adjusted through a grid device. The device includes: two groups of side supports are respectively arranged at both ends of the bottom installation component, and the specimen is vertically arranged between the two groups of side supports; two groups of bottom constraint plates, four simply supported constraint plates and two groups of out-of-plane adjustable grids are respectively arranged on both sides of the plate-shaped specimen, and the two groups of bottom constraint plates are respectively arranged at the bottom of the plate-shaped specimen, and the four simply supported constraint plates are respectively arranged in pairs at the left and right ends of the plate-shaped specimen; the bottom constraint plates are connected to the bottom installation component, and the simply supported constraint plates are connected to the corresponding side supports; two groups of end constraint plates are respectively arranged on both sides of the top of the plate-shaped specimen and are fixedly connected to the end loading plates arranged thereon, and the end loading plates are connected to the test loading equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material testing, and particularly relates to a compression test device for a composite laminate with a large length-thickness ratio. Background Art

[0002] In the current application process of composite material structures, laminate structures are mainly used. During the design process, it is necessary to test the compression performance after impact of laminates with a large length-thickness ratio for strength analysis.

[0003] Chinese Patent CN202010787333.9 discloses a test fixture for a simply-supported composite compression test piece, which is used to clamp a compression test piece and includes: a base, including an upper seat body and a lower seat body both having base chutes, and an upper semi-cylindrical rotating block is fitted in the base chute of the upper seat body, and a lower semi-cylindrical rotating block is fitted in the base chute of the lower seat body; and a frame, including symmetrically arranged left and right frames with frame chutes disposed between the upper seat body and the lower seat body, and a left semi-cylindrical rotating block is fitted in the frame chute of the left frame, and a right semi-cylindrical rotating block is fitted in the frame chute of the right frame. Among them, an upper sliding block is fixed on the upper semi-cylindrical rotating block, a lower sliding block is fixed on the lower semi-cylindrical rotating block, a left sliding block is fixed on the left semi-cylindrical rotating block, and a right sliding block is fixed on the right semi-cylindrical rotating block. The compression test piece is arranged between the upper sliding block, the lower sliding block, the left sliding block and the right sliding block and is fixed by the above four sliding blocks, and the distance between the sliding blocks is adjusted according to the thickness of the compression test piece.

[0004] Chinese Patent CN201921815032.1 discloses a tooling fixture for detecting the compression strength of composite materials, including an upper base, a lower base and a guide shaft. The upper base and the lower base are connected by the guide shaft. An upper hydraulic device, an upper left clamping block and an upper right clamping block are arranged on the lower end surface of the upper base; a lower hydraulic device, a lower left clamping block and a lower right clamping block are arranged on the lower base; a connecting rod is further arranged on the upper end surface of the upper base, and the connecting rod is used to connect with an external tensile machine. Using this tooling fixture for compression strength detection can effectively avoid phenomena such as instability and inaccurate centering of composite materials during the detection process, thereby improving the detection result of the compression strength, and further being able to characterize the true compression strength performance of composite materials.

[0005] The above two patents are both applicable to the compression test of small-sized laminates. The involved simply-supported devices are all connected by bolts, and the simply-supported devices and the lateral support devices are designed with long slots in the normal direction. The following disadvantages exist:

[0006] 1. For a composite laminate with a large length-thickness ratio at the moment of compression test failure, the instantaneous increase in out-of-plane load caused by axial failure instantaneously leads to an increase in out-of-plane load. The long slots and bolt connections cannot effectively prevent the original simply-supported device from undergoing out-of-plane torsion;

[0007] 2. The above existing patents adjust the flatness of the loading end surface by applying test materials such as copper sheets at the long and thick loading end surfaces in the traditional way, thereby converting it into the bending percentage that affects the long and wide loading plane. For composite laminates with a large length-to-thickness ratio, due to the long length of the test piece, the test piece is more likely to undergo local buckling before failure. Only constraining the boundary without constraining the middle test area cannot achieve the anti-buckling function of the overall long and wide surface, and effective test data cannot be obtained.

[0008] Therefore, it is necessary to study a compression test device for composite laminates with a large length-to-thickness ratio to address the deficiencies of the existing technology and solve or mitigate one or more of the above problems. Summary of the Invention

[0009] In view of this, the present invention provides a compression test device for composite laminates with a large length-to-thickness ratio, which can achieve simply supported constraints throughout the two sides during the compression test process of the composite laminate with a large length-to-thickness ratio, and the simply supported conditions are not likely to change at the moment of failure; at the same time, it can also achieve the adjustment of the flatness of the loading plane on the long and wide surfaces of the composite laminate.

[0010] The present invention provides a compression test device for composite laminates with a large length-to-thickness ratio, and the device includes a bottom mounting assembly, two groups of bottom constraint plates, two groups of side supports, four simply supported constraint plates, two groups of end constraint plates, an end loading plate, a plate-shaped specimen, and two out-of-plane adjustable grids for constraining the bending degree of the specimen;

[0011] The two groups of side supports are respectively arranged at both ends of the bottom mounting assembly, and the plate-shaped specimen is vertically arranged between the two groups of side supports;

[0012] The two groups of bottom constraint plates and the four simply supported constraint plates are respectively arranged on both sides of the plate-shaped specimen, and the two groups of bottom constraint plates are arranged at the bottom of the plate-shaped specimen, and the four simply supported constraint plates are pairwise arranged at the left and right ends of the plate-shaped specimen; the bottom constraint plates are connected to the bottom mounting assembly, and the simply supported constraint plates are connected to the corresponding side supports;

[0013] The two groups of end constraint plates are respectively arranged on both sides of the top of the plate-shaped specimen and are fixedly connected to the end loading plate arranged thereon, and the end loading plate is connected to the test loading equipment;

[0014] The two groups of out-of-plane adjustable grids are respectively arranged on both sides of the plate-shaped specimen and are fixedly connected to the simply supported constraint plates at the corresponding ends.

[0015] In the aspect and any possible implementation manner as described above, a further implementation manner is provided, and the bottom mounting assembly includes a base plate and a wear-resistant plate, and the wear-resistant plate is arranged on the upper surface of the base plate and the two are fixedly connected.

[0016] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The side support includes a bottom support member, a vertical support member, and an inclined support member;

[0017] Both the bottom support member and the vertical support member are plate-like structures; the inner end of the bottom support member is fixedly connected to the bottom end of the vertical support member to form an L-shaped structure;

[0018] The inclined support member is a right-angled triangular plate-like structure, and its two right-angled sides are respectively fixedly connected to the bottom support member and the vertical support member.

[0019] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The simply supported constraint plate includes a constraint plate in the middle and a plurality of transverse protrusions provided on both side walls of the constraint plate; the transverse protrusions on the side connected to the side support are inserted into the transverse grooves provided on the side support;

[0020] The simply supported constraint plate is also fixedly connected to the side support by bolts.

[0021] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The device further includes two sets of out-of-plane adjustable gratings for constraining the bending degree of the specimen; the two sets of out-of-plane adjustable gratings are respectively arranged on both sides of the plate-like specimen and are fixedly connected to the simply supported constraint plates at the corresponding ends.

[0022] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The out-of-plane adjustable grating includes a grating plate and grating mounting ears provided on the left and right sides of the grating plate; the grating mounting ears are perpendicular to the grating plate and are fixedly connected to the simply supported constraint plates at the corresponding ends.

[0023] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The grating mounting ear includes a plurality of rectangular plate-like embedding members arranged in sequence; the rectangular plate-like embedding members are sequentially inserted between the transverse protrusions provided on the inner side surface of the simply supported constraint plate, and the rectangular plate-like embedding members are fixedly connected to the simply supported constraint plate by bolts.

[0024] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The grating plate and the grating mounting ears of the out-of-plane adjustable grating are integrally and fixedly connected.

[0025] For the aspects and any possible implementation manners described above, a further implementation manner is provided. A gap is provided between the grating plate and the plate-like specimen.

[0026] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The width of the gap between the grating plate and the plate-like specimen is 0.1 mm.

[0027] For the aspects and any possible implementation manners described above, a further implementation manner is provided, where the lateral protrusion is a rectangular protrusion.

[0028] Compared with the prior art, one of the technical solutions in the above technical solutions has the following advantages or beneficial effects: The solution of the present invention can achieve that the two-side boundaries are kept simply supported constraints throughout the compression test process of the large aspect ratio laminate, with a simply supported constraint device with a rectangular track boundary. Compared with the traditional bolt-connected simply supported constraint device, the simply supported condition does not change at the moment of failure; at the same time, it can realize the adjustment of the loading flatness of the length and width surfaces of the composite laminate, change the adjustment of the bending percentage by end-face loading to achieve high-precision bending percentage loading by adjusting the loading flatness of the length and width surfaces, control the overall loading bending percentage within 5%, and realize the introduction of pure compression load for the large aspect ratio composite laminate.

[0029] Of course, it is not necessary for any product implementing the present invention to achieve all the above-described technical effects simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic diagram of a compression test device for a large aspect ratio composite laminate provided by an embodiment of the present invention;

[0032] Figure 2 It is a schematic structural diagram of the compression test device for a large aspect ratio composite laminate provided by an embodiment of the present invention after assembling the side supports;

[0033] Figure 3 It is a schematic structural diagram of the compression test device for a large aspect ratio composite laminate provided by an embodiment of the present invention after assembling the bottom constraint plate and the simply supported constraint plate on one side;

[0034] Figure 4 It is a schematic structural diagram of the compression test device for a large aspect ratio composite laminate provided by an embodiment of the present invention after assembling the specimen;

[0035] Figure 5 It is a schematic structural diagram of the compression test device for a large aspect ratio composite laminate provided by an embodiment of the present invention after assembling the bottom constraint plate and the simply supported constraint plate on the other side;

[0036] Figure 6It is a schematic structural diagram of the compression test device for large aspect ratio composite laminates after assembling the out-of-plane adjustable grid provided by an embodiment of the present invention.

[0037] Among them, in the figure:

[0038] 1. Substrate; 2. Wear-resistant plate; 3. Bottom restraint plate; 4. Side support; 5. Simple support restraint plate; 6. Out-of-plane adjustable grid; 7. End restraint plate; 8. End loading plate; 9. Specimen. Specific embodiments

[0039] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] The present invention provides a compression test device for large aspect ratio composite laminates, which prevents the out-of-plane torsion of the boundary simple support restraint device at the moment of composite material compression test failure through two contact forms of rectangular track and bolt connection; adjusts the loading flatness of the length and width surfaces of the composite laminate through the out-of-plane restraint grid, realizes the goal that the overall loading bending percentage of the test piece is better than 5%, and introduces the pure compression load of the large aspect ratio composite laminate.

[0042] The compression test device for large aspect ratio composite laminates, as Figure 1 shown, includes: substrate 1, wear-resistant plate 2, two bottom restraint plates 3, two side supports 4, two groups (a total of four, two in a group) of simple support restraint plates 5, two groups of out-of-plane adjustable grids 6, two groups of end restraint plates 7, end loading plate 8 and specimen 9.

[0043] In this device, the main connection between the parts is through bolts. The wear-resistant plate 2, the bottom restraint plate 3 and the side support 4 are fixed on the substrate 1 through bolts. The simple support restraint plate 5 is fixed in the side support 4 through bolts and a rectangular track, and the out-of-plane adjustable grid 6 is fixed in the side support 4 through bolts. The end restraint plate 7 and the end loading plate 8 are connected to the test loading equipment through bolts to realize the loading function.

[0044] The substrate 1 is a plate-like structure and is located at the bottom of the entire device. The wear-resistant plate 2 is also a plate-like structure, which is fixedly arranged on the upper surface of the substrate 1, and the two together form a bottom mounting assembly in a laminated manner.

[0045] There are two sets of side supports 4 in total. Each set of side supports includes a bottom support member, a vertical support member, and an inclined support member. Both the bottom support member and the vertical support member are rectangular plate-like structures. The inner end of the bottom support member is fixedly connected to the bottom end of the vertical support member to form an L-shaped structure. The inclined support member is a right-angled triangular plate-like structure, and the two right-angled sides are respectively fixedly connected to the bottom support member and the vertical support member.

[0046] There are two sets of simply supported restraint plates 5 in total. There are two in each set and they are respectively arranged on both sides of the vertical support member of the same side support. The plate-like specimen 9 is arranged between the two simply supported restraint plates and is clamped and fixed by the simply supported restraint plates on both sides. The simply supported restraint plates 5 are arranged vertically. A number of transverse grooves are provided on the inner side surface of the vertical support member of the side support 4, and the shape of the grooves is rectangular (that is, the rectangular track mentioned above). A number of transverse protrusions are provided on both side surfaces of the simply supported restraint plate 5, and the size of the transverse protrusions matches the size of the transverse grooves. During installation, the transverse protrusions are inserted into the transverse grooves, and then fixed with bolts.

[0047] Two sets of out-of-plane adjustable gratings 6 are respectively arranged on both sides of the specimen 9. Each set of out-of-plane adjustable gratings 6 includes a grating plate arranged parallel to the specimen 9 and grating mounting ears arranged at the left and right ends of the grating plate. The grating mounting ears are a number of small-sized rectangular plate-like embedded parts, and the rectangular plate-like embedded parts are perpendicularly and fixedly connected to the grating plate. Preferably, they are of an integral structure, that is, the grating plate and the grating mounting ears are integrally connected to form the entire out-of-plane adjustable grating 6. During assembly, the rectangular plate-like embedded parts are inserted between two adjacent transverse protrusions on the inner side surface of the simply supported restraint plate. The upper and lower two transverse protrusions play a role in positioning, restraining, and fixing the out-of-plane adjustable grating. At the same time, the rectangular plate-like embedded parts are fixedly connected to the simply supported restraint plate with bolts. A gap is left between the grating plate of the out-of-plane adjustable grating 6 and the specimen 9 to limit the bending percentage of the specimen 9 during the test.

[0048] There are two bottom restraint plates 3 in total, which are respectively arranged on both sides of the bottom of the specimen 9 to clamp and fix the bottom of the specimen 9. The bottom restraint plates 3 are arranged horizontally, and the left and right ends of each bottom restraint plate 3 are respectively fixedly connected to the corresponding side support 4. At the same time, the lower surface of the bottom restraint plate 3 is closely attached to the upper surface of the wear-resistant plate 2, and the bottom restraint plate 3 can be fixedly connected to the wear-resistant plate 2 and the substrate 1 with bolts.

[0049] Two sets of end restraint plates 7 are both arranged on the lower surface of the end loading plate 8, that is, the upper surface of the end restraint plates 7 is fixedly connected to the lower surface of the end loading plate 8. A gap is left between the two sets of end restraint plates 7, and the width of the gap matches the thickness of the specimen 9. The end loading plate 8 moves downward under the drive of the test loading device, and the upper end of the specimen 9 is inserted into the gap between the two end restraint plates 7 to realize the restraint of the upper end of the specimen 9. As the test loading device continues to move downward, loading is realized.

[0050] During the compression process, simply supported constraints on both sides of the test piece can be achieved through the simply supported constraint plate 5; through the cooperation of the out-of-plane adjustable grid 6 with the rectangular track and bolts of the simply supported constraint plate 5, the simply supported constraint plate 5 can be prevented from sliding out of the plane when bearing the instantaneous impact load of the test piece failure, and the simply supported boundary condition during the whole loading process can be realized; through the out-of-plane adjustable grid 6, the flatness adjustment of the loading plane on the long and wide surfaces of the test piece can be realized, changing from the conventional adjustment of the bending percentage by adjusting the end face to the adjustment of the bending percentage by the out-of-plane flatness, with higher test efficiency.

[0051] Implementation steps:

[0052] Select side supports 4 and simply supported constraint plates 5 with different heights according to the length dimension of the test piece, and select the bottom constraint plate 3 according to the thickness of the test piece.

[0053] Step 1: Fix the left and right side supports 4 on the base plate 1 and the wear-resistant plate 2, as Figure 2 shown, with the two side supports 4 arranged oppositely;

[0054] Step 2: According to the thickness of the test piece, fix the two simply supported constraint plates 5 on the same side of the two side supports on the corresponding side supports, and fix the bottom constraint plate 3 on the upper surface of the wear-resistant plate 2 and between the two simply supported constraint plates, as Figure 3 shown;

[0055] Step 3: Install the test piece (specimen 9), as Figure 4 shown;

[0056] Step 4: Install the two simply supported constraint plates 5 and one bottom plate constraint plate 3 on the other side, as Figure 5 shown; the total of four simply supported constraint plates 5 on both sides and two bottom plate constraint plates 3 clamp and fix the specimen 9 in the middle, playing a constraint role;

[0057] Step 5: Install the out-of-plane adjustable grid 6; leave a 0.1 mm gap between the surface of the out-of-plane adjustable grid 6 and the surface of the specimen 9; as Figure 6 shown;

[0058] Step 6: Install the end constraint plate 7 and the end loading plate 8 according to the thickness of the test piece;

[0059] Step 7: According to the bending percentage of the test piece during the compression loading process, adjust the position of the grid to ensure that the bending percentage of the test piece during the loading process is better than 5%.

[0060] The experimental device of the present invention was verified in the performance test project of a certain type of aircraft composite material. The verification results show that the rectangular track in the present invention can effectively achieve simply supported constraints at the boundary throughout the compression process, and the adjustable grid can quickly realize the adjustment of the loading bending percentage, ensuring that the loading plane bending percentage is within 5%.

[0061] The above has introduced in detail a compression test device for a large aspect ratio composite laminate provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

[0062] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such commodity or system. Without more limitations, the element defined by the statement "including one..." does not exclude the existence of another identical element in the commodity or system including the said element. "Substantially" means within an acceptable error range, and those skilled in the art can solve the said technical problem within a certain error range and basically achieve the said technical effect.

[0063] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "middle", "lateral", "vertical", etc. is based on the orientation or positional relationship shown in the drawings. In addition to being able to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present application can be understood according to specific circumstances. The term "and / or" used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

Claims

1. A compression test device for a composite laminate with a large length-thickness ratio, Characterized in that, The device includes a bottom mounting assembly, two groups of bottom restraint plates, two groups of side supports, four simply supported restraint plates, two groups of end restraint plates, an end loading plate, a plate-shaped specimen, and two out-of-plane adjustable gratings for restraining the bending degree of the specimen; The two groups of side supports are respectively arranged at both ends of the bottom mounting assembly, and the plate-shaped specimen is vertically arranged between the two groups of side supports; The two groups of bottom restraint plates and the four simply supported restraint plates are respectively arranged on both sides of the plate-shaped specimen, and the two groups of bottom restraint plates are respectively arranged at the bottom of the plate-shaped specimen, and the four simply supported restraint plates are respectively arranged in pairs at the left and right ends of the plate-shaped specimen; the bottom restraint plates are connected to the bottom mounting assembly, and the simply supported restraint plates are connected to the corresponding side supports; The two groups of end restraint plates are respectively arranged on both sides of the top of the plate-shaped specimen and are fixedly connected to the end loading plate arranged thereon, and the end loading plate is connected to the test loading equipment; The two groups of out-of-plane adjustable gratings are respectively arranged on both sides of the plate-shaped specimen and are fixedly connected to the simply supported restraint plates at the corresponding ends; The simply supported restraint plate includes a restraint plate in the middle and a number of transverse protrusions arranged on both side walls of the restraint plate; the transverse protrusions on the side connected to the side support are inserted into the transverse grooves arranged on the side support; The simply supported restraint plate is also fixedly connected to the side support by bolts; The out-of-plane adjustable grating includes a grating plate and grating mounting ears arranged on the left and right sides of the grating plate; the grating mounting ears are perpendicular to the grating plate and are fixedly connected to the simply supported restraint plates at the corresponding ends; The grating mounting ear includes a number of rectangular plate-shaped embedding parts arranged in sequence; the rectangular plate-shaped embedding parts are sequentially inserted between the transverse protrusions arranged on the inner side surface of the simply supported restraint plate, and the rectangular plate-shaped embedding parts are fixedly connected to the simply supported restraint plate by bolts.

2. The compression test device for a composite laminate with a large length-thickness ratio according to claim 1, Characterized in that, The bottom mounting assembly includes a base plate and a wear-resistant plate, and the wear-resistant plate is arranged on the upper surface of the base plate and the two are fixedly connected.

3. The compression test device for a composite laminate with a large length-thickness ratio according to claim 1, Characterized in that, The side support includes a bottom support member, a vertical support member, and an inclined support member; Both the bottom support member and the vertical support member are plate-shaped structures; the inner end of the bottom support member is fixedly connected to the bottom end of the vertical support member to form an L-shaped structure; The inclined support member is a right-angled triangular plate-shaped structure, and its two right-angled sides are respectively fixedly connected to the bottom support member and the vertical support member.

4. The compression test device for a composite laminate with a large length-thickness ratio according to claim 1, Characterized in that, The grating plate and the grating mounting ear of the out-of-plane adjustable grating are integrally fixedly connected.

5. The compression test device for a composite laminate with a large length-thickness ratio according to claim 1, Characterized in that, There is a gap between the grating plate and the plate-shaped specimen.

6. The compression test device for a composite laminate with a large length-thickness ratio according to claim 5, Characterized in that, The width of the gap between the grid plate and the plate-shaped specimen is 0.1 mm.

7. The compression test device for large aspect ratio composite laminates according to claim 1, characterized in that, the transverse protrusion is a rectangular protrusion.

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